1. Field of the Invention
The present invention relates to a method of separating lithium isotopes. More specifically, the invention relates to a method of lithium isotope separation by using a cryptand resin as an adsorbent.
2. Description of the Prior Art
Lithium consists of two stable isotopes, lithium-6 (.sup.6 Li) having a normal abundance of 7.5 at.% and lithium-7 (.sup.7 Li) with an abundance of 92.5 at.%. Recent years have seen an ever-increasing demand for these two lithium isotopes in nuclear energy applications. Lithium-6, with its high thermal neutron absorption cross section (ca. 947 barns) is used in shields against radioactive rays, control rods or lithium breeding blankets in fusion reactors. Lithium-7 having excellent thermodynamic and heat transfer characteristics and a low thermal neutron absorption cross section is used as an agent to control the acidity of the primary cooling water is pressurized-water reactors.
Conventionally, industrial lithium isotope separation is carried out by the amalgam method or displacement chromatography using a strong acid cation-exchange resin as an adsorbent. However, the amalgam method uses a large quantity of mercury and may cause environmental pollution or endanger the health of the related personnel. Conventional displacement chromatography is not highly effective because the single-stage separation factor is only 1.001 to 1.005. Therefore, it has long been desired to develop a new method for separating lithium isotopes without the defects of the conventional techniques.